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Comment by djrogers | Hacker News Reader

>Most places have shut down their 2G.

Citation? I haven't seen this to be the case in California - at least on Verizon.

There was a big story about it when ATT shut down their 2G network in SF since MUNI used that to report their locations.

http://sfist.com/2017/01/06/nextmuni_glitch_problem.php

Only AT&T shut down 2G. T-Mobile reiterated recently that their 2G network will probably be shut down after their 3G one, since it hardly uses any spectrum.

With places that have shutdown 2G, there is no "voice only" network anymore since 3G is required for the voice traffic.

T-Mobile and AT&T have very different planning. AT&T shut down their 2G because it mostly ran on 850mhz and this was needed for LTE and their legacy band 5 WCDMA (hspa) network.

T-Mobile mostly ran its 2G on 1900mhz, but had beefy midband spectrum holdings there and in AWS (and AWS-3) for most markets. Since you can run GSM down in like 200khz or so it's not a huge deal to have a small slice allocated to legacy voice fallback. You can't do that with 3G... you can thin it down but it's still going to need 3.8mhz or so. (T-Mobile has experience thinning HSPA down prior to the MetroPCS CDMA shutdown... which they had legacy CDMA running in guard bands)

Verizon and Sprint used to mostly be on CDMA-based technology. So their 3G 'EVDO' can't do calls.. it needs cdma2k layer to go back to, or full voLTE support. VZW has its shit together on voLTE, sprint will probably never launch volte at this rate.

Sorry was thinking up in Canada only Rogers maintains 2G still.

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